To make the poolish (a yeasted fermented starter dough), pour 75ml warm water into a large bowl. Tip in the yeast and sugar and stir to dissolve. Add the flour and stir to combine. Cover and leave in a warm spot for 1-1 1/2 hrs until doubled in size.

Heat the milk until just warmed through and steaming. In the bowl of a stand mixer, tip in the yeast, 1 tbsp of the sugar and the warmed milk and whisk gently. Leave for 10-15 mins until frothy. Add the remaining sugar, flour and egg yolks. Slowly beat together using the dough hook attachment for 5 mins until thoroughly combined. Add the poolish mixture, lemon zest, vanilla, honey and a large pinch of salt. Increase the mixer speed and add the butter gradually for a further 10-15 mins, until soft, smooth and elastic.

Lightly butter a clean bowl and transfer the dough to it. Cover and leave to rise for 1-2 hrs until doubled in size. Generously butter a 1kg pandoro tin, getting into all the crevices, add a couple of tbsp of flour and shake, dusting all over the inside and making sure it's covered. Knock the dough back in the bowl for 1 min, then shape into a ball. Transfer to the prepared tin, seam-side up. Cover and allow to rise for 1-2 hrs, until it almost reaches the top of the tin.

Heat the oven to 160C/140C fan/gas 3. Bake for 25-30 mins, then reduce the heat to 150C/130C fan/gas 2 and bake for a further 30 mins until golden brown on top and a skewer inserted into the middle comes out clean. Leave to cool in the tin for 10 mins, then transfer to a wire rack to cool completely. Dust generously with icing sugar to serve.